Escherichia coli Genosensor Based on Polyaniline

Abstract

Avidin-modified polyaniline (PANI) electrochemically deposited onto a Pt disk electrode has been utilized for direct detection of Escherichia coli by immobilizing a 5'-biotin-labeled E. coli probe (BdE) using a differential pulse voltammetric technique in the presence of methylene blue as a DNA hybridization indicator. Depending on the target sample and the sonication time, this BdE-avidin-PANI bioelectrode can be utilized to electrochemically detect a complementary target probe (0.009 ng/microL), E. coli genomic DNA (0.01 ng/microL) and 11 E. coli cells/mL in 60 s to 14 min (hybridization time) without using PCR and can be used 5-7 times at temperatures of 30-45 degrees C.

Quantitation of non-amplified genomic DNA by bead-based hybridization and template mediated extension coupled to alkaline phosphatase signal amplification

“…Arora et al reported an electrochemical approach combining methylene blue and a conducting polymer-based detection, which afforded detection limits for Escherichia coli gDNA of 3.5 fM. Importantly, extensive gDNA fragmentation (estimated size of 20 bp) was the key aspect not only on sensitivity but also on the response speed (Arora et al 2007). Another approach comprised the use of blocking oligonucleotides whose function was to prevent gDNA target re-hybridization.…”

Biosensors Based on Electropolymerized Films

“…In addition to the electropolymerization of biotin derivatives, another strategy consists in the covalent binding of one of the affinity partners onto polyaniline films. For instance, the anchoring of a biotinylated 20-mer oligonucleotide specific to Escherichia coli on an avidin-grafted polyaniline film led to an efficient electrochemical genosensor for E. coli cells without using PCR amplification [111]. The hybridization of E. coli cell lysate was detected by differential pulse voltammetry in the presence of methylene blue.…”

Peptide Nucleic Acid Immobilized Biocompatible Silane Nanocomposite Platform for Mycobacterium tuberculosis Detection

“…The hybridization studies of PNA-GOPS/ITO and PNA/ Fe 3 O 4 -GOPS/ITO electrodes have been performed by monitoring SWV of methylene blue as redox indicator [22,[44][45]. Methylene blue gets converted into leukomethylene blue at À0.35 V and is further reduced into methylene blue at À0.42 V (Figure 4a) [46].…”